1916] MEINECKE: PERIDERMIUM AND CRONARTIUM 235 



Examination of the galls produced in the experiments shows that the 

 aecia and the aeciospores are typical for Peridermium harknessii. 



Arthur 16 records under Cronartium Quercus (Brondeau) Schroet. 17 

 to 23 by 25 to 32ju for aeciospores on non-Californian pines. Arthur 

 and Kern 17 give 15 to 21 by 23 to 31ju for Peridermium harknessii and 

 17 to 23 by 25 to 32/z for Peridermium cerebrum. Later they 18 gave 

 15 to 24 by 23 to 33/z for Peridermium cerebrum, in which they now in- 

 clude Peridermium harknessii. The measurements of the aeciospores 

 of Peridermium harknessii resulting from direct aecial infection in our 

 experiments are as follows: 



(148) 11 to 26/z by 19 to 41/t (standard 17 to 22 by 24 to 



Fresh material of Peridermium harknessii collected on Pinus radiata at 

 the type locality near Monterey, California, measures: 



(50) 11 to 24/z by 22 to 37/z (17 to 20^ by 26 to 30ju). 



For comparison with these values the following measurements of aecio- 

 spores of Peridermium harknessii on various hosts including the two for- 

 mulas given above may be of interest: 



Pinus contorta (Rocky Mountains). 



(50) 15-24 x 19-43 (17-19 x 22-26) M . 



(50) 15-24 x 20-37 (19-20 x 22-26)/i. 



(50) 17-26 x 19-28 (19-22 x 20-26)^. 

 Pinus contorta (Sierra Nevada). 



(50) 13-22 x 19-33 (17-19 x 22-24) M . 



(50) 15-26 x 20-37 (17-20 x 22-26)ju. 



(50) 13-22 x 17-30 (15-19 x 22-26)/i. 



(50) 11-24 x 19-35 (17-20 x 22-26);*. 



(50) 15-26 x 19-31 (19-22 x 22-26)0. 

 (100) 13-30 x 19-33 (17-22 x 22-28)^. 

 Pinus jeffreyi. 



(40) 13-26 x 17-33 (17-20 x 20-26)/*. 

 Pinus ponder osa. 



(40) 11-22 x 20-35 (17-22 x 26-30)/*. 



(50) 15-24 x 16-37 (17-20 x 24r-30)/i. 



' North Am. Fl. 7 2 :122. 



17 Arthur, J. C. and Kern, F. D. North American species of Peridermium. Bui. 

 Torr. Bot. Club 33: 421 and 423. 



18 Mycologia 6: 134. 



19 (148) gives the number of spores measured, then follow the extreme values and 

 finally in parenthesis the standard values. See Meinecke, E. P., Spore measure- 

 ments. Science, n.s., 42: 430. 1915. 



